This invention relates to a diaphragm valve for compressed or liquified gases. More particularly, this invention relates to a diaphragm valve comprising a body containing a closing member with a sealing surface at the intersection of an inlet duct and an outlet duct for the passage of gas, a piston subjected to the action of elastic means, control means being connected to the closing member via both a pusher and a sealing diaphragm arranged between the pusher and the piston whereby the control means either reduces the passage between the inlet duct and the outlet duct counter to the action of the elastic means or enlarges the passage under the action of the elastic means.
There are various types of prior art valves suitable for use with compressed gas. These known valves essentially differ in their systems for sealing relative to the atmosphere. Each prior art valve has its advantages and disadvantages. For example, valves in which sealing is ensured by an O-ring or packing material have the advantage of longer service life and the disadvantage of progressive deterioration, that is, the gas leaks become progressively greater.
Another type of known prior art valves are those employing sealing diaphragms. The advantages of such diaphragm valves is that they can contain high pressures and are not attacked or affected by gases. On the other hand, the diaphragms have a relatively short life, and in the event of wear they break virtually instantaneously; resulting in a major gas leak when such a break occurs. Consequently, these valves do not ensure sufficient safety in uses where dangerous or toxic gases are involved.